(a) Technical Field
The present invention relates to a hydrogen discharge system for a fuel cell system. More particularly, the present invention relates to a hydrogen discharge system for a fuel cell system, which can ensure safety of a fuel cell vehicle by optimizing the dilution of hydrogen discharged from a fuel cell during discharge and ensure silence of the vehicle by reducing noise generated during discharge.
(b) Background Art
A fuel cell system can generally comprise a fuel cell stack for generating electricity, a fuel supply system for supplying fuel (hydrogen) to the fuel cell stack, an air supply system for supplying oxygen in the air as an oxidant required for an electrochemical reaction to the fuel cell stack, and a thermal management system for controlling the operation temperature of the fuel cell stack.
In exemplary fuel cell systems having the above configuration, a hydrogen recirculation blower is preferably connected to a hydrogen outlet of the fuel cell stack to recirculate hydrogen remaining after a reaction at a fuel electrode (anode) of the fuel cell stack to the fuel electrode to be reused.
Nitrogen or water accumulated in the fuel electrode is discharged from the fuel cell stack through a periodic purge.
Accordingly, in the operation of the fuel cell stack applied to a fuel cell vehicle, nitrogen or water accumulates in the fuel electrode (hydrogen electrode) and deteriorates the performance of the fuel cell stack, and thus it is necessary to ensure stable performance of the fuel cell stack through the periodic purge of the hydrogen electrode.
When the nitrogen or water is discharged from the fuel cell stack through the periodic purge, some residual hydrogen is discharged together with the nitrogen or water and, if the concentration of the discharged hydrogen is high, there may be a risk of explosion.
Accordingly, the concentration of the discharged hydrogen should be reduced or diluted within the range of explosion in order to avoid explosion.
For this purpose, conventionally, a diluter is provided in a hydrogen purge line to dilute the concentration of hydrogen in the air.
However, in the case where the diluter is used for example, hydrogen and air are merely mixed with each other, but the absolute amount of hydrogen is not reduced. Accordingly, the hydrogen may be accumulated in the inside of the vehicle and may cause safety accidents. A pipe channel for introducing air into the diluter or an air supply device may be provided, which increases the manufacturing cost and results in complexity of the piping.
As a post-treatment system for treating hydrogen discharged from the fuel cell stack, there has been conventionally proposed a catalyst combustion device or a flame combustion device, in which a large amount of air is introduced into a reactor to remove exhaust hydrogen discharged from the fuel cell stack. However, it results in complexity of the piping and increases the load of an air blower for supplying air to the catalyst combustion or flame combustion device.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.